The present invention generally relates to a heat exchanger, and more particularly, to a fin tube heat exchanger for use in an air conditioner or the like.
FIG. 1 depicts a conventional fin tube heat exchanger. As shown in FIG. 1, a heat exchanger 1 is provided with a plurality of fin plates 2 of aluminum spaced at regular intervals and a plurality of heat exchanger tube 3 extending through the fin plates 2. The heat exchanger tubes 3 are securely held in openings 4 formed in the fin plates 2 by any suitable means.
As shown in FIGS. 2 to 3, each fin plate 2 has a plurality of narrow cut-out strips extending across the direction of flow. These strips are raised from the plane in which the fin plate 2 lies for raising the heat exchanging performance. Raised strips 5-8 or 5-8' extend in a direction perpendicular to the direction of air flow shown by arrows A and B. The raised strips 5-8 are formed on the same side of each fin plate 2 in FIG. 2B whereas the raised strips 5-8' are form alternately on both sides of each fin plate 2 in FIG. 2C. In the case of the raised strips 5-8' as shown in FIG. 2C, water drops tend to stay substantially in the form of a bridge between adjacent raised strips 5-8', water drops do not drop from the fin plate until they grow into a considerable size.
Japanese Patent Laid-open Application No. 48-58434 discloses another configuration of raised strips as shown in FIGS. 3A to 3C. Similar to the heat exchanger disclosed in the foregoing Publication, raised strips 9-14 or 9-14' extend in a direction perpendicular to the direction of air flow shown by arrows A and B. The raised strips 9-14 are formed on the same side of each fin plate 2 in FIG. 3B whereas the raised strips 9-14' are formed alternately on both sides of each fin plate 2 in FIG. 3C. In the same fashion as disclosed in the foregoing Publication, water drops tend to stay between adjacent raised strips 9-14 or 9-14'. In this case, however, since each fin plate 2 is provided with a draining passage along the center line of a row of heat exchanger tubes, not as pattern as shown in FIGS. 2A to 2C, but the heat exchanging performance is still lowered.
As shown in FIG. 4, the raised strips are formed closer at the upper portion than at the lower portion of each fin plate, which causes water drops to readily drop along the fin plate and reduces the flows resistance. Accordingly, the extreme reduction of the heat exchanging performance which is primarily caused by the reduction in air quantity can be prevented.
In addition, since the raised strips 16a-18b on the one side are manufactured by a puncher and the raised strips 116a-118b on the other side are manufactured by the same puncher, it is possible to manufacture the raised strips at a low cost and in detail, but it is impossible to remove the water drops completely between the raised strips and the fin plate 15 or between adjacent raised strips.